Various techniques have been used in the past for making measurements on bodies. In addition to a wide variety of mechanical devices that have been used, in some cases for many years, there have also been techniques developed in which some kind of light pattern is directed onto the body and the shape or position of that light pattern sensed and, as a result, certain measurements related to the body sensed. Such prior techniques have proved adequate when making a limited number of localized measurements on a body but have not been able, at least without resorting to extremely complex arrangements, to make sufficient measurements that for example the shape of a large part or even all of a human body can be derived. Another technique that has been employed is to place a light source on one side of a body and an array of light detectors on the other side of the body. The boundary of the shadow cast by the body is then determined by the array of detectors. A technique of this kind is simpler than the optical techniques referred to above, but has the disadvantage of providing only a measurement of that part of the body that protrudes furthest. This makes interpretation and processing of data relatively complicated and also means that re-entrant surfaces on the body are not detected at all.